Page 628 - Air and Gas Drilling Manual

11-66 Air and Gas Drilling Manual
Equations 6-67 and 6-68 become, respectively,
.
a
i3 10
.
53 36
.
a i3 0 019
and
2 2
0 016 53 36 (.
2 635)
.
.
b i3
(
232 2 . ) 10 . 2 5
(.
0 319)
4
,
b i3 2 486
Equation 6-72 becomes
05 .
2 0 019) ( ,
2 375)
(.
.
.
65 660)
2 486) (
(, 2 ( , 586 29) 2 e 586 29 1
P i2 2 0 019) ( ,
2 375)
(.
.
e 586 29
2
P i2 61 184 lb/ft abs
,
P i2
p i2
144
p i2 429 4 psia
.
The pressure given above is the flowing air pressure at the top of the lumped drill
pipe body length inside the drill string in the openhole section of the borehole.
Inside the Drill String (7,000 ft to Surface)
The second drill string section increment is denoted by the length H 2. The
temperature at the bottom drill pipe tool joints lumped geometry length in the cased
section is
.
T 2 574 41˚R
The average temperature of the drill pipe tool joints lumped geometry along H 2 and,
thus, the temperature of the gas flow inside this drill string length is